JP4585299B2 - Rinsing liquid for lithography and resist pattern forming method using the same - Google Patents

Description

  The present invention is a novel lithography that is effective for reducing defects and pattern collapse by using a rinsing process after developing an image-exposed resist, and improving the draining speed to shorten the rinsing process time. And a resist pattern forming method using the same.

In recent years, along with miniaturization and integration of semiconductor devices, this fine processing light source can also form a resist pattern with higher resolution than conventional long-wavelength ultraviolet rays, from g-line (436 nm) to i-line (365 nm). From i-line to KrF excimer laser (248 nm), the wavelength has been shortened, and now the mainstream is moving to ArF excimer laser (193 nm), F ₂ excimer laser (157 nm), and electron beams such as EB and EUV. At the same time, processes and resist materials that can be adapted to these short wavelength light sources are being developed at a rapid pace.

  By the way, for conventional photoresists, for example, resists due to contamination such as sensitivity, resolution, heat resistance, depth of focus characteristics, resist pattern cross-sectional shape, and amine between the exposure and post-exposure heating (PEB). Deposition time stability that causes pattern shape deterioration, insulating film such as silicon nitride (SiN) film, semiconductor film such as polycrystalline silicon (Poly-Si) film, titanium nitride (TiN) film The silicon wafer provided with various films such as the metal film is required to improve the substrate dependency on which the resist pattern shape changes, and these have been solved to some extent, but are particularly important issues. There are many unresolved parts about defects.

  This defect is a resist pattern error that does not match the mask pattern detected when the developed resist pattern is observed from directly above with a surface defect observation device (defective resist pattern, scum, dust, uneven color, pattern As the number of defects increases, the yield of semiconductor elements decreases. Even if the above resist characteristics are good, mass production of semiconductor elements is difficult as long as the defects cannot be resolved. It will be something.

  There are various possible causes for this defect, one of which is due to microbubbles during development and the other is the reattachment of insoluble matter once removed during rinsing.

  As a method for reducing such defects, improvement of the positive resist composition itself used for pattern formation has been proposed (see Patent Document 1). However, if the composition is changed in this way, the process itself must be changed. Therefore, it is not preferable.

  In addition, a method of applying a defect treating agent containing a hydrophobic group and a hydrophilic group, that is, a surfactant, is known when forming a resist pattern (see Patent Document 2). The top part is rounded, the cross-sectional perpendicularity is lowered, and there is a drawback that the resist layer is thinned by the processing. Usually, in the development processing, since the developing solution is supplied through a centralized pipe, there are many types. This method is not appropriate in a semiconductor manufacturing factory where a resist must be used.

  Further, in a photolithography development process, a developer containing an organic base containing no metal ions and a nonionic surfactant as a main component is used to reduce defects (see Patent Document 3) or to hardly volatile with a molecular weight of 200 or more. In order to obtain a sufficient effect, a method (see Patent Document 4) for reducing defects by processing after exposure and before heating using an aqueous solution containing an aromatic sulfonic acid and having a pH of 3.5 or less is also known. Not reached.

  On the other hand, by using a rinse agent composition having an amino group or imino group and a hydrocarbon group having 1 to 20 carbon atoms in the molecule and containing a nitrogen-containing compound having a molecular weight of 45 to 10,000, a rinsing step or drying is performed. Although it is also known to suppress the collapse and damage of the resist pattern generated in the process (see Patent Document 5), the above-described defect cannot be reduced by such a rinse agent composition. Moreover, although the rinse liquid containing an ethylene oxide or a propylene oxide type activator is also known (refer patent document 6), interaction with a hydrophilic group and water is weak, and a pattern collapse suppression effect is not acquired.

JP 2002-148816 A (Claims and others) JP 2001-23893 (Claims and others) JP 2001-159824 A (Claims and others) JP 2002-323774 A (Claims and others) JP-A-11-295902 (Claims and others) JP 2004-184648 A (Claims and others)

  In view of such circumstances, the present invention reduces the surface defects of the product, so-called defects when forming a photoresist pattern using lithography technology, suppresses pattern collapse in water rinse, and is resistant to electron beam irradiation. The purpose of the present invention is to provide a rinsing liquid that is effective for improving the yield of products by preventing the shrinkage of the pattern, and can accelerate the drainage speed and increase the production efficiency. Is.

  As a result of extensive research on the rinsing liquid used when forming a resist pattern by lithography, the present inventors have used a conventional rinsing liquid by including a water-soluble nitrogen-containing heterocyclic compound in the rinsing liquid. The present inventors have found that the above-mentioned various drawbacks associated with such cases can be overcome, and the present invention has been made based on this finding.

（式中のＸはＮとともに五員若しくは六員複素環又は縮合環を有する五員又は六員複素環を形成する環構成員子、Ｒはハロゲン原子、水酸基又はアミノ基、ｎは０又は１〜３の整数である）
で表わされる水溶性含窒素複素環化合物を含有する水性溶液からなるリソグラフィー用リンス液、及び
（Ａ）基板上にホトレジスト膜を設ける工程、
（Ｂ）該ホトレジスト膜に対しマスクパターンを介して選択的に露光処理する工程、
（Ｃ）露光後加熱処理する工程、
（Ｄ）アルカリ現像する工程、
及び
（Ｅ）前記したリソグラフィー用リンス液で処理する工程
を順次施すことを特徴とするレジストパターン形成方法を提供するものである。 That is, the present invention has the general formula

(Wherein X is a ring member forming a 5-membered or 6-membered heterocyclic ring having a 5- or 6-membered heterocyclic ring or a condensed ring together with N, R is a halogen atom, hydroxyl group or amino group, n is 0 or 1 It is an integer of ~ 3)
A rinsing liquid for lithography comprising an aqueous solution containing a water-soluble nitrogen-containing heterocyclic compound represented by: (A) a step of providing a photoresist film on the substrate;
(B) a step of selectively exposing the photoresist film through a mask pattern;
(C) a step of heat treatment after exposure,
(D) a step of alkali development,
And (E) Provided is a resist pattern forming method characterized by sequentially performing the step of processing with the above-described lithography rinse solution.

Next, the present invention will be described in more detail.
The rinsing liquid for lithography of the present invention must contain the water-soluble nitrogen-containing heterocyclic compound represented by the above general formula (I). For example, pyrrole, thiazole, oxazole, imidazoline, imidazole, pyridine, pyrazine And at least one compound selected from among pyrimidine, pyridazine, piperazine, indole, isoindole, quinoline, triazole and partial hydrides thereof.

  Examples of the halogen atom in the above general formula include a fluorine atom and a chlorine atom, and examples of the amino group include a primary amino group or a secondary amino group having a lower alkyl group having 1 to 4 carbon atoms as an N-substituent. Is preferred.

  Examples of the water-soluble nitrogen-containing heterocyclic compound include not only aromatic heterocyclic compounds in which the heterocyclic ring is completely unsaturated, but also those in which the heterocyclic ring is completely or partially hydrogenated, and The oxo compound is also included.

Accordingly, examples of the water-soluble nitrogen-containing heterocyclic compound suitably used in the present invention include imidazolidinone, caprolactam, 2,5-dimethylpiperazine, 2,6-dimethylpiperazine, 3-chloropyridine, and 4-chloropyridine. And cyanuric chloride, 2,5-dimethylpiperazine, 3,5-dimethylpyrazole, 2-piperidone, 3-pyridinol, pyridylamine, methylpiperidine, methylpyridine, methoxypyridine, pyrazolone, quinolylamine and the like.
These water-soluble nitrogen-containing heterocyclic compounds may be used alone or in combination of two or more.

  The rinsing liquid for lithography of the present invention is prepared by dissolving the above water-soluble nitrogen-containing heterocyclic compound in an aqueous solvent, that is, water alone or a mixed solvent of water and a water-miscible organic solvent.

  As the water-miscible organic solvent, alcohol solvents such as methanol, ethanol, isopropanol, propanol, or glycol solvents such as ethylene glycol, propylene glycol, diethylene glycol and the like are used. The content of the water-miscible organic solvent is suitably in the range of 0.01 to 10% by mass, preferably 0.1 to 5% by mass, based on the mass of water.

  The concentration of the water-soluble nitrogen-containing heterocyclic compound in the rinsing liquid for lithography of the present invention is 0.1 ppm to 10% by mass, preferably 5 ppm to 3% by mass, particularly 10 ppm to 1%, based on the total mass of the rinsing liquid. A mass% range is suitable.

The rinsing liquid for lithography of the present invention can further contain a water-soluble resin as desired. Examples of the water-soluble resin include vinyl alcohol, vinyl acetamide, (meth) acrylamide, methyl (meth) acrylamide, ethyl (meth) acrylamide, propyl (meth) acrylamide, dimethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) ) Homopolymer or copolymer of at least one monomer selected from acrylate, quaternized dimethylaminoethyl (meth) acrylate, vinylimidazole, vinylimidazoline, vinylpyridine, vinylpyrrolidone, vinylmorpholine and vinylcaprolactam There is.
The mass average molecular weight of these homopolymers or copolymers is 500 to 1,500,000, preferably 1,000 to 50,000.

  The concentration of the water-soluble resin is selected in the range of 0.1 ppm to 10% by mass, preferably 0.5 ppm to 5% by mass, based on the total mass of the rinse liquid.

  In the rinsing liquid for lithography of the present invention, an acidic substance or an alkaline substance may be added to further improve storage stability, and an anionic surfactant or a nonionic surfactant may be added to improve coating characteristics. it can.

  Examples of the acidic substance include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, glycolic acid, oxalic acid, fumaric acid, maleic acid, phthalic acid, peracetic acid, sulfuric acid, trifluoroacetic acid, and ascorbic acid. . The liquidity of this acidic solution is preferably adjusted to pH 6 or less.

  The alkaline substance is preferably an organic base such as an organic amine or quaternary ammonium hydroxide, the organic amine is monoethanolamine or 2-aminoethoxyethanol, and the quaternary ammonium hydroxide is tetramethylamine. Examples thereof include ammonium hydroxide, tetraethylammonium hydroxide, 2-hydroxyethyltrimethylammonium hydroxide, tetrapropylammonium hydroxide, methyltripropylammonium hydroxide, tetrabutylammonium hydroxide, and methyltributylammonium hydroxide. The alkaline solution should have a pH of 8 or higher.

  Examples of the anionic surfactant include N-higher alkyl pyrrolidone and higher alkyl benzyl quaternary ammonium salt, and examples of the nonionic surfactant include higher fatty acid polyethylene oxide condensate. Particularly preferred is at least one alkylene oxide compound selected from polyoxyalkylene glycols and monoalkyl ethers thereof. These surfactants are used in a proportion of 0.001 to 0.5% by mass, preferably 0.005 to 0.1% by mass, based on the total amount of the pretreatment developer.

Next, in order to form a resist pattern using the lithography rinse liquid of the present invention,
(A) a step of providing a photoresist film on the substrate;
(B) a step of selectively exposing the photoresist film through a mask pattern;
(C) a step of performing post-exposure heating (PEB) treatment;
(D) A step of alkali development and (E) A step of processing with the above-described rinsing liquid for lithography are sequentially performed.

The step (A) is a step of forming a photoresist film on the substrate.
As a substrate material, a silicon wafer is usually used, but among others known as semiconductor device substrates such as aluminum, titanium-tungsten alloy, aluminum-silicon alloy, aluminum-copper-silicon alloy, silicon oxide, silicon nitride. It can be used by arbitrarily selecting from.

  In order to provide a photoresist film on this substrate, for example, a solution of a chemically amplified photoresist composition generally used in the manufacture of semiconductor devices is dried with a spinner or the like so that the dry thickness becomes 0.5 to 10 μm. Apply.

  In the step (A), the coating solution thus prepared is applied to a substrate, and then pre-baked at 70 to 150 ° C. for 30 to 150 seconds.

  Next, in step (B), the resist film formed in step (A) is selectively exposed through a mask pattern to form a latent image. This exposure process is performed by irradiating active rays such as ArF excimer laser and KrF excimer laser.

  In the step (C), the positive resist film on which the latent image is formed by light irradiation in the step (B) is subjected to post-exposure heating (PEB). This treatment is usually performed at a temperature of about 70 to 150 ° C. for 30 to 150 seconds.

Next, the resist film that has been heat-treated after exposure in this manner is alkali-developed in accordance with a conventional method in step (D).
As the developer for the alkali development, an aqueous solution of tetraalkylammonium hydroxide, preferably tetramethylammonium hydroxide is used. As this concentration, a range of 1 to 5% by mass, preferably 2 to 3% by mass is selected, but the optimum concentration is around 2.38% by mass. The treatment temperature is usually room temperature, for example, a temperature in the range of 10 to 30 ° C, particularly 23 ° C.

  In step (E), the photoresist film developed in step (D) is treated with the above-described rinsing liquid for lithography. This treatment is performed by immersing a substrate carrying a resist pattern generated by development in a rinsing solution, or by applying or spraying this rinsing solution on the resist pattern film surface. An application method that does not require a new process in the semiconductor element production line, such as a spin coating method, is advantageous.

  By this processing of the rinsing liquid for lithography of the present invention, redeposition of the polymer dissolved and removed during development can be prevented, and defects in the resulting resist pattern can be reduced.

  Since semiconductor devices are usually mass-produced and throughput is an important condition, this processing time is preferably as short as possible. Therefore, this processing time is selected in the range of 1 to 30 seconds.

In the method of the present invention, it is advantageous to use the above-described fluorine-containing nitrogen-containing heterocyclic compound as the water-soluble nitrogen-containing heterocyclic compound contained in the rinsing liquid because the treatment time can be further shortened.
That is, in the case of rinsing with a rinsing liquid for lithography containing a fluorine-containing nitrogen-containing heterocyclic compound, if it is treated with a subsequent rinsing liquid with pure water, draining of water, that is, shaking off of water is improved. When the content of the fluorine-containing nitrogen-containing heterocyclic compound in the rinsing liquid is increased to some extent, it is about 1/3 of 3 seconds as compared to about 10 seconds when the other water-soluble nitrogen-containing heterocyclic compound is used. It can be shortened to the extent.

In the method of the present invention, when the step (E) is performed after the step (D), (F) a rinsing step with pure water can be further added as desired.
Usually, when forming a resist pattern, one of the causes of defects is that alkali-insoluble components in the resist composition are precipitated during water rinsing after alkali development and adhere to the photoresist film surface after the resist pattern is formed. However, in the method of the present invention, after the development, the resist pattern surface is treated with the rinsing liquid for lithography of the present invention to impart hydrophilic characteristics to the resist pattern surface. It is speculated that reattachment can be suppressed, and the defects of the reattachment system are particularly reduced.

  When the resist pattern surface treated by the method of the present invention is further treated with a rinse solution containing an alcohol-based solvent-soluble fluorine compound, for example, a water-soluble fluorocarbon compound, the pattern collapse is effectively prevented to produce a high-quality product. There is an advantage that you can.

  According to the present invention, defects caused when a pattern is formed using a photoresist are reduced, the yield of the product is improved, resistance to electron beams is imparted, and pattern shrinkage due to electron beam irradiation is suppressed. High dimensional controllability can be maintained. Furthermore, the effect of improving water drainage and preventing pattern collapse can be achieved.

Next, the best mode for carrying out the present invention will be described by way of examples, but the present invention is not limited to these examples.
In addition, the physical-property value in each example is measured with the following method.

(1) Defect number reduction ratio The number of defects in a resist pattern rinsed with each rinse solution sample using a surface defect observation apparatus [product name “KLA-2351” manufactured by KLA (KLA) Tencor Corporation]. (A) was measured and expressed as a percentage (%) with respect to the number of defects (B) when rinsed with pure water only, that is, (A / B) × 100.

(2) Shaking time A positive resist (product name “TARF-P6111”, manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied to an 8-inch silicon wafer at a thickness of 1800 mm, and 2.38 mass% tetramethylammonium without exposing it. After treating with an aqueous hydroxide solution (liquid temperature 23 ° C.) for 60 seconds, a test rinse solution was applied to the surface at 2000 rpm for 6 seconds, and pure water was applied at 500 rpm for 3 seconds to prepare a sample. The time to shake off was expressed in seconds.

(3) Electron beam resistance When a line having a width of 130 nm is formed on a silicon substrate and irradiated repeatedly 1 to 30 times using a length measurement SEM (manufactured by Hitachi High-Technology Corporation, product name “S-9200”). The line width was measured.

An antireflection film-forming coating solution [Brewer, product name “ARC-29A”] is applied onto an 8-inch silicon wafer, and heat-treated at 215 ° C. for 60 seconds to form an antireflection film having a thickness of 77 nm. Then, a photoresist (manufactured by Tokyo Ohka Kogyo Co., Ltd., product name “TARF-P6111”) was applied on the antireflection film and heat-treated at 130 ° C. for 90 seconds to form a 460 nm-thick photoresist film. .
The photoresist film thus obtained was subjected to an exposure process through a 130 nm line and space mask pattern using an exposure apparatus (product name “Nikon NSR-S302A” manufactured by Nikon Corporation), and then 90 ° C. at 90 ° C. For 2 seconds.
Subsequently, a 130 nm line and space resist pattern was formed by developing for 60 seconds at 23 ° C. using an aqueous 2.38 mass% tetramethylammonium hydroxide solution.

Next, a rinsing solution made of a 100 ppm aqueous solution of imidazoline was prepared, and rinse treatment was performed by applying it to the surface of the resist pattern at 2000 rpm for 7 seconds.
The number of defects of the resist pattern obtained in this way was measured using a surface defect observation apparatus [product name “KLA-2351” manufactured by KLA Tencor Co., Ltd.]. Was about 6%.

  By adding imidazoline to a 0.1% by mass aqueous solution of polyvinylpyrrolidone (mass average molecular weight 10,000) at a ratio of 25 ppm, 50 ppm and 100 ppm based on the total mass, and stirring, the rinsing liquid for lithography (I), (II ) And (III) were prepared.

ARC29A [manufactured by Brewer] was applied on the silicon wafer and heat-treated at 215 ° C. for 60 seconds to form an antireflection film having a thickness of 77 nm. On this antireflection film, TARF-P6111 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was applied to form a 460 nm-thick photoresist film.
The substrate on which the photoresist film was formed was subjected to an exposure treatment with 193 nm exposure light using Nikon S302A (manufactured by Nikon Corp.), followed by a heat treatment at 130 ° C. for 90 seconds.
After completion of the exposure, development processing was performed at 23 ° C. for 60 seconds using an aqueous 2.38 mass% tetramethylammonium hydroxide solution.

Next, using the rinsing liquid for lithography of the present invention obtained in Example 2 and a rinsing liquid containing only polyvinyl pyrrolidone or polyvinyl alcohol for comparison at a concentration of 0.1% by mass, the resist obtained by the above development treatment After the pattern was dropped on the pattern at 500 rpm for 3 seconds and rinsed, it was further rinsed with pure water for 20 seconds under the same conditions.
The physical properties of the resist pattern rinsed in this way are shown in Table 1.

  The present invention can be used for manufacturing semiconductor devices such as LSI and ULSI using lithography technology.

Claims (11)

General formula

(Wherein X is a ring member forming a 5-membered or 6-membered heterocyclic ring having a 5- or 6-membered heterocyclic ring or a condensed ring together with N, R is a halogen atom, hydroxyl group or amino group, n is 0 or 1 It is an integer of ~ 3)
A rinsing solution for lithography comprising an aqueous solution containing a water-soluble nitrogen-containing heterocyclic compound represented by the formula: The water-soluble nitrogen-containing heterocyclic compound is at least selected from pyrrole, thiazole, oxazole, imidazoline, imidazole, pyridine, pyrazine, pyrimidine, pyridazine, piperazine, indole, isoindole, quinoline, triazole and partial hydrides thereof. one rinse solution for lithography according to claim 1, wherein the. The rinsing liquid for lithography according to claim 2 , wherein the water-soluble nitrogen-containing heterocyclic compound is ring-substituted with a halogen atom, a hydroxyl group or an amino group. The rinsing liquid for lithography according to any one of claims 1 to 3 , wherein the content of the water-soluble nitrogen-containing heterocyclic compound is 0.1 ppm to 10% by mass based on the total mass of the rinsing liquid for lithography. The rinsing liquid for lithography according to any one of claims 1 to 4 , wherein the solvent is a mixed solvent of water and a water-miscible organic solvent. The rinsing solution for lithography according to claim 5, wherein the water-miscible organic solvent is an alcohol-based or glycol-based organic solvent. The rinsing liquid for lithography according to claim 5 or 6, wherein a mixing ratio of the water-miscible organic solvent is 0.01 to 10% by mass based on the mass of water. The rinsing liquid for lithography according to any one of claims 1 to 7 , further comprising a water-soluble resin. The rinsing liquid for lithography according to claim 8 , wherein the content of the water-soluble resin is 0.1 ppm to 10% by mass based on the total mass of the rinsing liquid for lithography. (A) a step of providing a photoresist film on the substrate;
(B) a step of selectively exposing the photoresist film through a mask pattern;
(C) a step of heat treatment after exposure,
(D) a step of alkali development,
And (E) A resist pattern forming method comprising sequentially performing the step of treating with the rinsing liquid for lithography according to any one of claims 1 to 9 . The resist pattern forming method according to claim 10, further comprising (F) rinsing using pure water.